Render animation in png's give same frames
thx for the file, found the problem:  

two things:
1. bake cloth simulation: "Bake All Dynamics", otherwise eevee wont simulate it as  Blender would do it by pressing play in 3D View.
2. Your Render step in the Output-Menue was at 1000, so you would only get 1 frame. Just put it to 1 and everything should work fine.  

just for completness: i used "blender-2.80.0-git.957b4547aeeb-windows64" build to test it.